The instant application should be granted the priority date of Feb. 19, 2008, the filing date of the corresponding International patent application PCT/EP2008/001264.
The invention relates to a method for controlling longwall mining operations having a face conveyor, at least one extraction machine, and a hydraulic shield support in underground coal mining.
The control of longwall operations during extraction generally is concerned with the best possible exploitation of the provided machine capacities while avoiding shutdowns, an automation of the required control procedures being provided if possible, in order to avoid flawed human decisions. Approaches to automation of the control are in development and/or already in use, such as sensory boundary layer detection/control, learning step methods, recognition and control of the stepping path of the stepping shield support, automated stepping of the shield support, and automatic maintenance of a predefined set inclination of the face conveyor.
One problem in the automation of controlling a longwall mining operation is, inter alia, in so-called boundary layer recognition, i.e., the recognition of the transition between coal and country rock, connected with the establishment of whether the employed extraction machine is working beyond the extraction of the coal in the overlying stratum and/or in the footwall, i.e., in the country rock. The corresponding finding is important, on the one hand, with respect to the reduction of the caving in of rock during the extraction work, because every engagement in the horizontal of overlying stratum and footwall increases the caving in of additional rocks. Furthermore, in general an engagement of the extraction machine into the overlying stratum is also to be avoided because this provides or increases the danger of caving in from the overlying stratum, and such a caving in from the overlying stratum disturbs or makes more difficult the support work using the shield support frames following the extraction front. This also applies correspondingly for a cut into the footwall level or layer of the seam opening. On the other hand, however, it can be necessary when driving through faults or driving through saddles or troughs to perform a planned footwall cut, in order to ensure a sufficient seam opening for the passage of the longwall equipment, and in this case the monitoring of the extent of the particular footwall cut is desirable.
The invention is therefore based on the object of disclosing a method according to the features mentioned at the beginning, which allows monitoring of a cut of the extraction machine in the country rock.